Howard has been out of action since picking up a calf strain just before half-time of December’s 1-0 defeat to Stoke, with Robles deputising for the past seven Premier League games and two FA Cup matches in his absence.
While there were serious concerns over how he would fare during an extended run between the posts, the Spaniard has gotten over a somewhat nervous start to earn widespread praise for his contributions.
On a run of three consecutive clean sheets – the same amount as Howard has recorded in his 18 top-flight appearances this season – some have called for him to keep his spot ahead of the now-fit American, but those demands look to have fallen on deaf ears.
“When Tim is fit, he is No1,” said Martinez at his pre-match press conference. “I have total faith in him and it is great to see training well and having a huge influence on the squad again.
“It is different to an outfield position. In goal you need a bit of stability. Joel Robles is a young man with a real good future. I am very proud of how he has done.”
Nevertheless, with Howard’s form coming in for considerable criticism over the first half of the season, one has to wonder whether Martinez is making the right decision.
During his time in the net, Robles has conceded over 0.5 goals per game less than his counterpart, while making both more saves and punches.
In addition, the former Spain Under-21 international is right up there alongside Howard when it comes to claiming crosses, despite some labelling it an area of weakness prior to him being thrust into the starting role.
The area where it's clear that Robles lags behind is his distribution but, in terms of overall impact, there's a good argument to make that he has outperformed the ex-Manchester United shot-stopper during his short-term spell.
Aged just 24, he can still afford to bide some time on the bench but, with Howard showing clear signs of decline ahead of turning 36 in March, it might be sooner rather than later that Martinez needs to hand his compatriot the number one gloves.
With Manchester United star David De Gea and West Ham United's Adrian well-established as their respective clubs' first-choice options, Robles could soon join them to make it a trio of Spanish keepers starring in the English top-flight week in, week out.